Saturday, October 1, 2016

D-Walker build part 2 - Body work

Part 2 of D-Walker build - foam, razors, glue and paint.

"Father, give me legs"

D-Walker's body panels are all made of 1/2" thick EVA foam mats. The side panels are doubled up for rigidity. The EVA foam was mostly leftover from my Destiny Warlock. I had bought more than I needed at Sam's Club because they were cheap, only to later realize that the quality of EVA foam varies. The majority of foam I had to use for D-Walker was subpar - it has more pinholes, and seems to be slightly more "stale" as compared to the softer and denser Costco foam. The cheaper foam does not cut as easily or smoothly, resulting in jagged edges and wearing out blades much more quickly. I completed the body with my leftover pieces, but ended up buying one more pack of good foam to complete the legs and feet (~$22). The cheap foam is also harder to form with heat, but luckily I didn't have to do any of that for D-Walker anyway.

The rectangles next to certain bolts would have been protruding hooks - I omitted these as I felt they could easily break.

I started with cardboard templates, more or less freehand - I measured the angles and eyeballed the rest. My D-Walker is about a foot shorter from nose to tail than in-game, because the extra length would have placed the head and arms too far forward. Those parts would make up a good portion of the body's weight, so I wanted to centralize that weight more. The side panels are longer than a single square mat, so the outer layer is two pieces joined by contact cement (this was another limiting factor to the total length of the side panels). The inner layer is three pieces, so that no two seams are in the same place.

The hidden inner panels use the interlocking mat edges, which are otherwise almost always thrown out.

The side panels are attached to the PVC frame with these little plastic tabs. The tabs are from a large food container, thick enough to be bent and hold some weight. I cut slots in the side panel's inner layer and superglued the tabs in place before contact cementing the inner layer to the outer layer. Each side panel has four tabs with holes for two zip ties each, and it has proven to be pretty sturdy. The side panels are easily removable, but are still sturdy enough to help hold the center panels in place.

My bedroom/robotics facility.

The side panels were then given some dimension. Every panel went on the belt sander to angle and clean up the edges (I use a 600 grit silicon carbide belt, it comes out very smooth). I also always remove the foam mat's textured side around the edges so that it is not visible anywhere. The C-shaped part visible on the inside of the left panel in the above photo shows how little claws grab on to the PVC. These hooks were cut a little smaller than the PVC circumference, making a surprisingly snug fit.

The cemented-together set of panels that covers the center of the body (top, front and underside) uses the same hooks - and nothing else - to stay in place. The center panels are not attached to the side panels, again so that the sides can be removed. This means all of the foam panels had to be snug, straight, and symmetrical so no gaps showed. There is also a cockpit panel that covers the area around the controls, which again uses the same hooks and friction fitment to stay in place. I guess I don't have pics of either of these panels separately.

The leg panels are pretty simple. They needed to appear to be semi-reverse jointed, but not restrict my movement too much. I knew the body would obstruct most of D-Walker's crotch area, so I opted to just mount the main pieces on a sturdy pair of pants (I think they are a denim-cotton blend). In the above picture you can see how rivets and fender washers hold pieces of Celtec on to the pants, and then foam panels were contact cemented to the mounting plates.

This was not as awkward to wear and walk in as it looks.

This turned out well enough, although the right leg suffered some damage when I got a little tangled going down some stairs at Amazing Hawaii Comic Con (a risky maneuver in this costume, by the way). A piece of foam that helped keep the thigh panel properly oriented ripped off, which is why it looks askew in pictures at the con.
The feet were the type of part that I left unplanned until pretty much the very end. They are basically EVA foam sandals that are hot glued to an old pair of sneakers. I spruced them up with some damping pistons liberated from some old exercise equipment that I found on the side of my street. The lower end is tied to my shoelace, and the upper end is tied to a washer on the pants. The results are floppy, heavy detail pieces that look cool if they are sitting correctly, but aren't really necessary. Sorry, no pics, but there is a video in part 6 that you can see these parts in.

All foam pieces Plastidipped. The cockpit panel mentioned is visible on the top of the pile.

All foam pieces were painted with 4-5 layers of PVA (regular old Elmer's white glue), then 2-3 coats of Plastidip, followed by four flavors of spray paint, acrylic weathering, and then a matte clear coat. The PVA glue needs to be very slightly diluted with water to let it flow into small holes while not clumping up. The foam will have a semi-shiny, semi-rigid shell if it has enough layers of PVA on it. If I felt a piece still looked too foamy (porous), I added yet another layer. The more PVA the better, as long as it doesn't obscure any detail. The Plastidip just needs to evenly cover the PVA layer.

The brown and sand colored paints were leftover from my MIDA Multitool project, although I eventually had to buy additional cans. The oregano green was purchased to match the rider's camo pattern, and even though the camo doesn't have brown in it, I added it to DW's paint job because it looked better.

I used masking tape to weather this stencil because Vaseline is messy.

Pretty sweet spray booth huh? Space is expensive in Hawaii, so my work areas are cramped and only barely suitable.

Above are the side panels after their final clear coat. The raised details are 3mm Celtec and EVA foam. The bolt details are polyurethane resin casts. I was still manufacturing Snake arms while working on this project, so I would always pour a little resin from each cast into an open-face mold of various size bolt heads. The largest "bolt" on the side panels is actually a chunk of scrap Celtec that was produced when I drilled out the holes in D-Walker's head with a spade bit, glued to a thin piece of wooden dowel. I thought they looked cool and specialized, so I found a use for them.

Original and duplicate bolts heads.

All of the bolts had to be separately painted and added after the foam painting stage, because I did not want to add them first and then mask each little bolt off. The rust drips are a pretty cool detail in D-Walker's design, appropriate for hardware that lives on an oil platform. I had some iron powder lying around for ages for this exact rust effect, but I somehow misplaced it and ended up going with the imperatively quicker method of orange and brown acrylic paint. I watered it down a lot and just saturated any area that needed rust, letting it drip down naturally if possible and wiping up the excess.

The good old method of rubbing brown and black acrylic paint into every crevice and then wiping the majority away was also used to dirty everything up. I used the Vaseline masking technique to make all of the scars in the white paint, but I didn't use it with any other color (for those unfamiliar, you make little blobs and streaks of Vaseline, paint over it and let it dry, then wipe it away, leaving ragged-edged chips in the paint). This is partly because I didn't want the paint job to look TOO messy or beat up, partly because it is faithful to the in-game model, and entirely because that would be a lot of greasy Vaseline to clean up. I suppose the in-game explanation could be that the white paint, used to stencil on the numbers and whatnot, is a lower quality paint than the powder-coated (speculation) colors, and is added afterwards. Maybe.

The Diamond Dog and Starside logos were vinyl decals printed by my brother using equipment at his job. ($0!) Thank you BROTHERRRRRR!!